fix: use `React.JSX` instead of `JSX` for React 19 support

[dlehmhus]

Motivation

React has removed the JSX global namespace in React 19, as a result, it needs to be accessed via the React global namespace now React.JSX.

Summary

Access JSX via React.JSX.

[changeset-bot[bot]]

🦋 Changeset detected

Latest commit: ed1c539f9e073ae345153a5f4fab403011c655d1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 9 packages

Name	Type
@linaria/react	Patch
@linaria/atomic	Patch
linaria	Patch
@linaria/testkit	Patch
linaria-website	Patch
esbuild-example	Patch
rollup-example	Patch
vite-example	Patch
webpack5-example	Patch

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